1. Field of the Invention
The present invention is generally concerned with telecommunication systems and more particularly with a system for integrating mobile terminals, in particular cellular terminals, into a private telecommunication system.
2. Description of the Prior Art
In the present context the term xe2x80x9cmobile terminalsxe2x80x9d means terminals designed to function in a public mobile telecommunication system, for example the Global System for Mobile communications (GSM) in the case of cellular terminals, a public mobile telecommunications system of this kind comprising a network, also known as the Public Land Mobile Network (PLMN), and mobile terminals, also known as mobile stations, able to access that network.
xe2x80x9cPrivate telecommunication systemxe2x80x9d means a system formed of one or more Private Automatic Branch Exchanges (PABX) connected to a private network and terminals, generally fixed terminals, connected to the PABX.
A system for integrating mobile terminals into a private telecommunication system must be able to set up incoming or outgoing calls concerning the mobile terminals using a private numbering scheme specific to the private telecommunication system.
One solution to this problem is to modify one or other of the entities that constitute the Public Land Mobile Network (PLMN) and the PABX, to enable them to set up such calls. Clearly a solution of the above kind is not optimized in terms of flexibility, however.
Another solution, described in document WO 96/21329, avoids modifying a PABX by associating it with a server which for incoming calls converts a private number into a public mobile subscriber number. The above document merely indicates that outgoing calls are routed to a server of the above kind.
Document WO 94/26073 states that outgoing calls are routed to a server of the above kind merely upon recognition that the terminals belong to the public telecommunication system, this being indicated by the mobile subscriber database specific to the public mobile telecommunication system (the GSM""s Home Location Register (HLR), for example).
A drawback of a solution of the above kind is that the PLMN must be modified to assure such routing. Also, routing outgoing calls is not optimized in the case of calls to users of the public system.
A further drawback of a solution of the above kind is that management of such mobile users by the private telecommunication system manager is not optimized. Monitoring the rights of these users is not optimized because the data relating to any incoming and/or outgoing call restrictions concerning such users cannot be centralized, but must be introduced into the mobile terminal (or into cards such as SIM cards associated with the terminals) and/or said server, and it is also difficult to monitor mobile call times for such calls as are authorized.
A solution which avoids modifying the PLMN in Virtual Private Network (VPN) systems consists in associating the PLMN with a server performing private number to public number conversion for outgoing calls, calls thereafter being routed to the private network via the public network or Public Switched Telephone Network (PSTN).
A drawback of a solution of the above kind is that routing outgoing calls is not optimized for calls to users of the private system.
Also, VPN systems necessitate modification of the PABX so that private number to public mobile subscriber number conversion is possible for outgoing calls and to enable users of such mobile terminals to access services offered by the private system.
An aim of the present invention is to avoid the various drawbacks mentioned above.
The present invention therefore consists in a system for integrating mobile terminals into a private telecommunication system, including first and second servers respectively associated with a public mobile telecommunication system accessed by the mobile terminals and with the private telecommunication system, enabling setting up of incoming or outgoing calls relating to the mobile terminals and in accordance with a private numbering scheme specific to the private telecommunication system and holding first and second service data relating to mobile terminal users, and means for cooperation between the first and second servers for setting up calls relating to the mobile terminals and/or managing service data.
In accordance with another feature of the invention, the cooperation means include means in the first server for converting a private number used for an outgoing call into a public number usable by the mobile telecommunication system and enabling the call to be routed to the second server.
In this way the PLMN does not have to be modified to route outgoing calls to the private system, in contrast to the prior art referred to above.
The public number obtained after conversion advantageously includes the private number in a sub-address field of an address itself including a public number allocated to the second server.
In accordance with another feature of the invention, the first service data include data for monitoring the rights of mobile terminal users and the mobile call times of such users.
This optimizes management of mobile users by the private telecommunication system manager in that it can be centralized and located as close as possible to the mobile call supervisory elements.
In accordance with another feature of the invention, the cooperation means include a network interconnecting the servers and enabling distribution of service data from one server to at least one other server.
Thus service data management is also optimized because it can be centralized in a way that avoids the risk of errors.
Other objects and features of the present invention will become apparent on reading the following description of one embodiment of the invention given with reference to the accompanying drawings.